I don’t get Found Poetry, but I do see it as equivalent to collage in the visual arts. I don’t get collage either, but a lot of people I respect do. I see my lack of “getting” as my failure of perspective, not theirs. The killer punch is Kurt Schwitters.
I agree with Ira Lightman; attribution in found poetry is necessary. Having said that, I wonder what to do about clichés: too much poetry I hear includes them, but never attributes the original author. I don’t like clichés in poetry, and am tempted to start a campaign to get those people who use clichés to attribute them, if only to encourage them to grasp the idea of spotting flaws in their work. However, I fear doing so would enable some of the more egotistical lazy ones to start describing themselves as found poets, so giving themselves credit when none is due, & damaging found poetry in the process.
Similarly, I don’t get why it’s wrong to reuse groups of words, but wrong to not to reuse individual words.